First a disclaimer: I have never used the Expect Perl module and can't help you on that.

Otherwise, it seems that you have a default terminal line-length problem, not really a Perl problem. This might be a simple configuration issue, but I do not have enough information on your system to suggest corrections (assuming I could, which is far from guaranteed).

One possible work-around is to reduce the length of your command line through the use of Unix environment variables.